JP2019109329A - Laminated body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laminate capable of reducing the curl of a laminate containing a polarizing plate and a release film, and preventing the release film from floating. SOLUTION: A polarizing plate and a release film are laminated in this order, the polarizing plate includes a protective film, a polarizer, and an adhesive layer in this order, and the pressure-sensitive adhesive layer is a release film. The thickness of the polarizer is 15 μm or less, the puncture strength of the protective film is 3.0 gf / μm or more, and the pressure-sensitive adhesive layer and the release film are arranged. A laminate having a creep force of 4.5N or more and 15N or less. [Selection diagram] Fig. 1

Description

  The present invention relates to a laminate.

  Liquid crystal display devices and organic EL display devices are used in various display devices by taking advantage of features such as low power consumption, low voltage operation, and lightness and thinness. The liquid crystal display device includes a pair of polarizing plates disposed on the viewing side and the back side of the liquid crystal cell. The organic EL display device includes a polarizing plate (circularly polarizing plate) disposed on the viewing side of the organic EL display element.

  The polarizing plate is marketed as a laminate having a peelable surface protection film (also called a protect film) and a peelable film (also called a separate film) attached to the surface for preventing stains and scratches on its surface. It is common to When producing a display device, the release film is peeled off and the exposed pressure-sensitive adhesive layer is laminated on a display element. Therefore, the release film needs to be in close contact with the polarizing plate without peeling off until use. However, depending on the type of the pressure-sensitive adhesive layer, there is a problem that the peelable film peels off from the polarizing plate at the end of the laminate due to strong adhesion during long-term storage, that is, the peelable film rises.

  In addition, the laminate may have an asymmetric configuration (a configuration in which the thickness is different, the type of material is different, or the number of layers is different) with reference to the polarizer, and curl may occur. Curling of the laminate may degrade the yield of producing a display device. Heretofore, the curling of the laminate has been controlled by the tension when bonding the surface protective film to the polarizing plate. Recently, with the reduction in thickness of display devices, members constituting a laminate become thinner and curling is more likely to occur, and the control of tension alone is insufficient for solving such a problem.

  Patent Document 1 describes an optical laminate in which a pressure-sensitive adhesive layer, a polarizer protective sheet, a polarizer, a light transmitting substrate, a shielding layer, and a hard coat layer are laminated in this order. It is described that the occurrence of curling due to humidity change can be prevented by using a polyester base material having a small dimensional change rate as the light transmitting base material. In addition, it is described that the cellulose ester film is stressed in a high temperature and high humidity environment, and the entire liquid crystal cell curls. Patent document 1 aims at the curl reduction of the liquid crystal panel after bonding a polarizing plate to a liquid crystal cell, and does not consider the curl of optical laminated body itself. In addition, the lift of the release film is not considered in Patent Document 1.

  Patent Document 2 describes a polarizing plate in which a pressure-sensitive adhesive layer, a transparent support, an iodine-based PVA polarizer, and a hard coat film are laminated in this order. The hard coat film described in Patent Document 2 can reduce the curing hardness of the film and the curl of the hard coat film due to curing shrinkage even when the transparent support is thinned. Patent Document 2 aims to reduce the curl of a hard coat film alone, and does not consider the curl of the entire laminate when the hard coat film is applied to a polarizing plate. In addition, lifting of the release film is not considered in Patent Document 2

JP, 2014-6447, A JP, 2016-64399, A

  An object of the present invention is to provide a laminate in which the curl of a laminate including a polarizing plate and a release film can be reduced and floating of the release film is less likely to occur.

[1] A laminate in which a polarizing plate and a release film are laminated in this order,
The polarizing plate includes a protective film, a polarizer, and an adhesive layer in this order,
The pressure-sensitive adhesive layer is disposed at a position adjacent to the release film,
The thickness of the polarizer is 15 μm or less.
The puncture strength of the protective film is 3.0 gf / μm or more,
The laminated body whose creep force of the said adhesive layer and the said peeling film is 4.5 N-15 N.
[2] The laminate according to [1], wherein the moisture permeability of the protective film is 600 g / m ² · 24 hr or less.
[3] The laminate according to [1] or [2], wherein the protective film has a hard coat layer on the side opposite to the release film side.
[4] The laminate according to [3], wherein a surface resistance value of the hard coat layer is 1.0 × 10 ⁷ Ω / sq or more and 1.0 × 10 ¹⁰ Ω / sq or less.
[5] Any one of [1] to [4], wherein the protective film contains at least one selected from cellulose resins, polycarbonate resins, polyolefin resins, polyethylene terephthalate resins, and methyl methacrylate resins The laminated body as described in.
[6] The laminate according to any one of [1] to [5], which has a surface protective film on the side opposite to the release film side based on the polarizing plate.

  ADVANTAGE OF THE INVENTION According to this invention, the curl of the laminated body containing a polarizing plate and a peeling film can be made small, and the laminated body which floating of a peeling film does not raise easily can be provided.

It is a schematic sectional drawing which shows an example of the laminated constitution of a laminated body. It is a schematic sectional drawing which shows an example of the laminated constitution of a display apparatus. It is the (a) top view and the (b) side view showing the shape of a test piece when measuring creep force.

<Laminate>
FIG. 1 is a schematic cross-sectional view showing an example of the layer configuration of the laminate of the present invention. The adhesive layer is not shown in FIGS. 1 and 2. As shown to Fig.1 (a), the laminated body 100 of this embodiment has the layer structure on which the polarizing plate 10 and the peeling film 60 were laminated | stacked. The polarizing plate 10 includes a protective film 20, a polarizer 11, and an adhesive layer 30 in this order. The pressure-sensitive adhesive layer 30 is disposed at a position adjacent to the release film 60, in other words, the pressure-sensitive adhesive layer 30 is a layer formed on the outermost surface of the polarizing plate 10.

  The laminate of the present invention can further include other layers. As shown in FIG. 1 (b), the laminate 101 of the present embodiment has a surface protection film 50 on the side opposite to the release film 60 side with respect to the polarizing plate 10.

  As shown in FIG. 1 (a), the laminate may have the protective film 20 only on one side of the polarizer 11, and as shown in FIG. 1 (b), the laminate is polarized. The protective films 20 and 21 may be provided on both sides of the child 11 respectively.

  As shown in FIG. 1 (b), the polarizing plate 10 in the laminate 101 of the present embodiment has a hard coat layer 40. The hard coat layer 40 is preferably formed on the protective film 20, that is, the protective film 20 preferably has the hard coat layer 40 on the side opposite to the release film 60 side. The hard coat layer 40 may be disposed adjacent to the surface protective film 50, and the hard coat layer 40 may be a layer formed on the outermost surface of the polarizing plate 10.

Hereinafter, each member which comprises the laminated body of this invention is demonstrated.
(Polarizer 11)
The polarizer 11 used in the present invention usually has a step of uniaxially stretching a polyvinyl alcohol resin film, a step of adsorbing a dichroic dye by dyeing the polyvinyl alcohol resin film with a dichroic dye, and dichroism It manufactures through the process of processing the polyvinyl alcohol-type resin film by which the pigment | dye was adsorbed with boric acid aqueous solution, and the process washed with water after the process by boric acid aqueous solution.

  As polyvinyl alcohol-type resin, what saponified polyvinyl acetate type resin can be used. Examples of polyvinyl acetate resins include polyvinyl acetate, which is a homopolymer of vinyl acetate, and copolymers of vinyl acetate and other monomers copolymerizable therewith. Examples of other monomers copolymerizable with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and acrylamides having an ammonium group.

  The degree of saponification of the polyvinyl alcohol-based resin is usually about 85 to 100 mol%, preferably 98 mol% or more. This polyvinyl alcohol-based resin may be modified, and, for example, polyvinyl formal modified with aldehydes, polyvinyl acetal or the like can also be used. The polymerization degree of the polyvinyl alcohol resin is usually about 1,000 to 10,000, and preferably about 1,500 to 5,000.

  What formed the polyvinyl alcohol-type resin into a film is used as a raw film of the polarizer 11. The polyvinyl alcohol-based resin can be formed into a film by a known method. The thickness of the raw film is preferably about 5 to 35 μm, more preferably 5 to 20 μm, considering that the thickness of the obtained polarizer 11 is 15 μm or less. When the film thickness of the raw film is 35 μm or more, it is necessary to increase the draw ratio at the time of producing the polarizer, and the dimensional shrinkage of the obtained polarizer 11 tends to be large. On the other hand, when the film thickness of the raw film is 5 μm or less, the handling property at the time of stretching is lowered, and defects such as cutting tend to occur easily during the production.

  The uniaxial stretching of the polyvinyl alcohol-based resin film can be performed before, simultaneously with, or after the dyeing of the dichroic dye. If uniaxial stretching is performed after dyeing, this uniaxial stretching may be performed before or during the boric acid treatment. Moreover, you may uniaxially stretch in these several steps.

  In uniaxial stretching, the polyvinyl alcohol-based resin film may be uniaxially stretched between rolls having different peripheral speeds, or may be uniaxially stretched using a heat roll. The uniaxial stretching may be dry stretching in which stretching is performed in the atmosphere, or may be wet stretching in which a polyvinyl alcohol resin film is swollen using a solvent and in a swollen state. The stretching ratio is usually about 3 to 8 times.

  As a method of dyeing a polyvinyl alcohol-based resin film with a dichroic dye, for example, a method of immersing a polyvinyl alcohol-based resin film in an aqueous solution containing a dichroic dye is employed. Specifically, iodine or a dichroic dye is used as the dichroic dye. The polyvinyl alcohol-based resin film is preferably subjected to immersion treatment in water prior to the dyeing treatment.

  When using iodine as a dichroic dye, the method of immersing and dye | staining a polyvinyl-alcohol-type resin film the aqueous solution containing an iodine and potassium iodide is employ | adopted normally. The content of iodine in this aqueous solution is usually about 0.01 to 1 part by weight per 100 parts by weight of water. In addition, the content of potassium iodide is usually about 0.5 to 20 parts by weight per 100 parts by weight of water. The temperature of the aqueous solution used for dyeing is usually about 20 to 40 ° C. Moreover, the immersion time (staining time) to this aqueous solution is usually about 20 to about 1,800 seconds.

On the other hand, when using a dichroic dye as a dichroic dye, the method of immersing and dye | staining a polyvinyl alcohol-type resin film the aqueous solution containing water-soluble dichroic dye is employ | adopted normally. The content of the dichroic dye in this aqueous solution is usually about 1 × 10 ⁻⁴ to 10 parts by weight, preferably about 1 × 10 ⁻³ to 1 part by weight, per 100 parts by weight of water. The aqueous solution may contain an inorganic salt such as sodium sulfate as a dyeing assistant. The temperature of the aqueous dichroic dye solution used for dyeing is usually about 20 to 80 ° C. Moreover, the immersion time (staining time) to this aqueous solution is usually about 10 to 1,800 seconds.

  The boric acid process after dyeing | staining with a dichroic dye can be normally performed by immersing the dyed polyvinyl alcohol-type resin film in boric-acid containing aqueous solution.

  The amount of boric acid in the boric acid-containing aqueous solution is usually about 2 to 15 parts by weight, preferably 5 to 12 parts by weight, per 100 parts by weight of water. When iodine is used as the dichroic dye, this boric acid-containing aqueous solution preferably contains potassium iodide. The amount of potassium iodide in the boric acid-containing aqueous solution is usually about 0.1 to 15 parts by weight, preferably about 5 to 12 parts by weight, per 100 parts by weight of water. The immersion time in the boric acid-containing aqueous solution is usually about 60 to 1,200 seconds, preferably about 150 to 600 seconds, and more preferably about 200 to 400 seconds. The temperature of the boric acid-containing aqueous solution is usually 50 ° C. or higher, preferably 50 to 85 ° C., and more preferably 60 to 80 ° C.

  The polyvinyl alcohol resin film after boric acid treatment is usually washed with water. The water washing process can be performed, for example, by immersing a boric acid-treated polyvinyl alcohol resin film in water. The temperature of water in the water washing treatment is usually about 5 to 40 ° C. The immersion time is usually about 1 to 120 seconds.

  After washing with water, drying treatment is performed to obtain the polarizer 11. The drying process can be performed using a hot air dryer or a far infrared heater. The temperature of the drying treatment is usually about 30 to 100 ° C, preferably 50 to 80 ° C. The drying time is usually about 60 to 600 seconds, preferably 120 to 600 seconds.

  In addition, at least one process selected from stretching, dyeing, boric acid treatment, washing with water, and drying in a polyvinyl alcohol-based resin film in the manufacturing process of the polarizer 11 is described in, for example, JP-A-2012-159778. You may carry out according to the method to be. In the method described in this document, a polyvinyl alcohol-based resin layer to be the polarizer 11 is formed by coating a substrate film with a polyvinyl alcohol-based resin.

  In the present invention, the thickness of the polarizer 11 constituting the polarizing plate is 15 μm or less. By setting the thickness of the polarizer 11 to 15 μm or less, the contraction force of the polarizer itself can also be reduced, so peeling under a high temperature environment can also be prevented. In the present invention, the polarizer 11 is preferably 13 μm or less, and may be 10 μm or less. The thickness of the polarizer 11 is usually 2 μm or more in that it is easy to impart desired optical characteristics. According to the present invention, even if the thickness of the polarizer 11 is as thin as 15 μm or less, curling of the laminate can be suppressed.

(Protective film 20, 21)
The protective film 20 is a protective film disposed on the side opposite to the adhesive layer 30 side with respect to the polarizer 11, that is, on the viewing side. The protective film 21 is a protective film that can be disposed between the polarizer 11 and the pressure-sensitive adhesive layer 30.

  The puncture strength of the protective film 20 is 3.0 gf / μm or more, preferably 3.5 gf / μm or more, and more preferably 4.0 gf / μm or more. The upper limit is not particularly limited, but is usually 15.0 gf / μm or less, and may be 10.0 gf / μm or less. By setting the puncture strength of the protective film 20 in the above range and making the creep force of the pressure-sensitive adhesive layer 30 and the release film 60 in the range described later, the curl of the laminate can be reduced.

  The puncture strength of the protective film can be measured as follows. For the piercing test, a tester equipped with a needle with a tip diameter of 1 mmφ and 0.5 R is used. Secure the protective film to the tester by sandwiching the protective film with two jigs with a circular hole in the center. The needle is vertically lowered relative to the protective film through the hole of the jig to measure the strength when the protective film is broken. Test conditions are a piercing speed of 0.33 cm / sec under an environment of a temperature of 23 ± 3 ° C. By performing a piercing test on 12 test pieces and dividing the average value by the thickness of the protective film, it is possible to determine the piercing strength per unit film thickness of the protective film. When the protective film has a hard coat layer, the puncture strength is measured in the state where the hard coat layer is formed.

The moisture permeability of the protective film 20 is 600 g / m ² · 24 hr or less, preferably 550 g / m ² · 24 hr or less. The lower limit is not particularly limited, but is usually 0 g / m ² · 24 hr or more, more typically 10 g / m ² · 24 hr or more, and may be 100 g / m ² · 24 hr or more. By setting the moisture permeability of the protective film 20 in the above-described range, it is possible to reduce the width at which the moisture content of the polarizing plate changes in accordance with the surrounding environment. As a result, expansion or contraction of the polarizing plate can be reduced, and curling of the laminate can be reduced. The moisture permeability of the protective film can be measured under the conditions of a temperature of 40 ° C. and a relative humidity of 90% by the cup method defined in JIS Z 0208. When a protective film has a hard-coat layer, moisture permeability is measured in the state in which the hard-coat layer was formed.

  The protective films 20 and 21 are made of, for example, a resin film, and can be made of a transparent resin film. In particular, it is preferable to use a material that is excellent in transparency, mechanical strength, thermal stability, moisture shielding property, and the like. When a layered product has a hard court layer, protective film 20 can also be used as a substrate which forms a hard court layer. In the present specification, “transparent” means that the transmittance is 80% or more in the visible light range. In addition, as the protective films 20 and 21, it is also possible to use a cured layer of an active energy ray-curable resin composition, a brightness enhancement film, or a retardation film.

  When the protective films 20 and 21 are respectively laminated on both sides of the polarizer, the same protective films may be used, or different protective films may be used.

  The resin for forming the protective films 20 and 21 is not particularly limited. For example, methyl methacrylate resin, polyolefin resin (chain polyolefin resin, cyclic polyolefin resin), polyvinyl chloride resin Cellulose resin, styrene resin, acrylonitrile butadiene styrene resin, acrylonitrile styrene resin, polyvinyl acetate resin, polyvinylidene chloride resin, polyamide resin, polyacetal resin, polycarbonate resin, modified polyphenylene ether Films comprising a polybutylene terephthalate resin, a polyethylene terephthalate resin, a polysulfone resin, a polyethersulfone resin, a polyarylate resin, a polyamideimide resin, and a polyimide resin And the like.

  These resins can be used alone or in combination of two or more. In addition, these resins may be used after any suitable polymer modification, and examples of the polymer modification include copolymerization, crosslinking, molecular terminal modification, stereoregularity control, and reaction between different polymers. And denaturing such as mixing including the case of

  Among these, the material of the protective films 20 and 21 preferably contains at least one selected from cellulose resins, polycarbonate resins, polyolefin resins, polyethylene terephthalate resins, and methyl methacrylate resins. The polyolefin resin mentioned here includes a chain-like polyolefin resin and a cyclic polyolefin resin.

  The methyl methacrylate resin is a polymer containing 50% by weight or more of methyl methacrylate units. The content of methyl methacrylate units is preferably 70% by weight or more, and may be 100% by weight. The polymer having 100% by weight of methyl methacrylate units is a methyl methacrylate homopolymer obtained by polymerizing methyl methacrylate alone.

  The methyl methacrylate resin can be generally obtained by polymerizing a monofunctional monomer containing methyl methacrylate as a main component in the presence of a radical polymerization initiator. In the polymerization, if necessary, a polyfunctional monomer or a chain transfer agent may be coexistent.

  The monofunctional monomer copolymerizable with methyl methacrylate is not particularly limited, and examples thereof include ethyl methacrylate, butyl methacrylate, cyclohexyl methacrylate, phenyl methacrylate, benzyl methacrylate and methacrylic acid 2. -Ethylhexyl and methacrylates other than methyl methacrylate such as 2-hydroxyethyl methacrylate; methyl acrylate, ethyl acrylate, butyl acrylate, cyclohexyl acrylate, phenyl acrylate, benzyl acrylate, 2-acrylate Ethylhexyl and acrylic esters such as 2-hydroxyethyl acrylate; methyl 2- (hydroxymethyl) acrylate, methyl 3- (hydroxyethyl) acrylate, ethyl 2- (hydroxymethyl) acrylate, And hydroxyalkyl acrylic esters such as butyl 2- (hydroxymethyl) acrylate; unsaturated acids such as methacrylic acid and acrylic acid; halogenated styrenes such as chlorostyrene and bromostyrene; vinyl toluene and α-methylstyrene Unsaturated styrenes such as acrylonitrile and methacrylonitrile; unsaturated acid anhydrides such as maleic anhydride and citraconic anhydride; and unsaturated imides such as phenyl maleimide and cyclohexyl maleimide it can. Such monomers may be used alone or in combination of two or more.

  The polyfunctional monomer copolymerizable with methyl methacrylate is not particularly limited. For example, ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate Esterified with acrylic acid or methacrylic acid at both terminal hydroxyl groups of ethylene glycol or its oligomers such as tetraethylene glycol di (meth) acrylate, nona ethylene glycol di (meth) acrylate, and tetradecaethylene glycol di (meth) acrylate Those obtained by esterifying both terminal hydroxyl groups of propylene glycol or an oligomer thereof with acrylic acid or methacrylic acid; neopentyl glycol di (meth) acrylate, hexanediol di (meth) acrylate Acrylic acid or methacrylic acid obtained by esterifying hydroxyl group of dihydric alcohol such as silylate and butanediol di (meth) acrylate; bisphenol A, alkylene oxide adduct of bisphenol A, or both terminal hydroxyl groups of these halogen-substituted products Esterified with acrylic acid or methacrylic acid; those obtained by esterifying polyhydric alcohols such as trimethylolpropane and pentaerythritol with acrylic acid or methacrylic acid, and glycidyl acrylate or glycidyl methacrylate at the terminal hydroxyl group of these polyhydric alcohols Those obtained by ring-opening addition of an epoxy group; dibasic acids such as succinic acid, adipic acid, terephthalic acid, phthalic acid, and halogen-substituted products thereof, and alkylene oxide adducts thereof, etc. Those with an epoxy group of glycidyl acrylate or glycidyl methacrylate by ring-opening addition; allyl (meth) acrylate; and aromatic divinyl compounds such as divinylbenzene and the like. Among them, ethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, and neopentyl glycol dimethacrylate are preferably used.

  As the methyl methacrylate resin, a resin obtained by reaction between functional groups copolymerized with the resin is also used. As the reaction, for example, intramolecular demethanol condensation reaction of methyl ester group of methyl acrylate and hydroxyl group of methyl 2- (hydroxymethyl) acrylate or carboxyl group of acrylic acid and 2- (hydroxymethyl) acrylic The intramolecular dehydration condensation reaction of the hydroxyl group of methyl acid and the like can be mentioned.

  The polyethylene terephthalate resin means a resin in which 80 mol% or more of the repeating unit is composed of ethylene terephthalate, and may contain other dicarboxylic acid component and diol component. Other dicarboxylic acid components include, but are not limited to, for example, isophthalic acid, 4,4'-dicarboxydiphenyl, 4,4'-dicarboxybenzophenone, bis (4-carboxyphenyl) ethane, adipic acid Sebacic acid, 1,4-dicarboxycyclohexane and the like.

  Other diol components include, but are not limited to, propylene glycol, butanediol, neopentyl glycol, diethylene glycol, cyclohexanediol, ethylene oxide adduct of bisphenol A, polyethylene glycol, polypropylene glycol, and polytetramethylene glycol Etc.

  These dicarboxylic acid components and diol components can be used in combination of two or more if necessary. Also, hydroxycarboxylic acids such as p-hydroxybenzoic acid and p-β-hydroxyethoxybenzoic acid can be used in combination. In addition, as another copolymerization component, a dicarboxylic acid component containing a small amount of an amide bond, a urethane bond, an ether bond, a carbonate bond or the like, or a diol component may be used.

  Methods of producing polyethylene terephthalate resins include direct polycondensation of terephthalic acid and ethylene glycol (and optionally other dicarboxylic acids or other diols), dialkyl esters of terephthalic acid and ethylene glycol (and optionally, Transesterification with other dicarboxylic acid dialkyl esters or other diols followed by polycondensation, and ethylene glycol esters of terephthalic acid (and optionally other dicarboxylic acids) (and optionally) A method of polycondensing other diol ester in the presence of a catalyst is employed. Furthermore, if necessary, solid phase polymerization can be performed to improve the molecular weight or reduce low molecular weight components.

  Cyclic polyolefin resins are obtained, for example, by polymerizing cyclic olefin monomers such as norbornene and other cyclopentadiene derivatives in the presence of a catalyst. It is preferable to use such a cyclic polyolefin resin because a protective film having a predetermined retardation value, which will be described later, can be easily obtained.

  As cyclic polyolefin resin, for example, ring-opening metathesis polymerization is carried out using norbornene or its derivative obtained by Diels-Alder reaction from cyclopentadiene and olefins or (meth) acrylic acid or its esters as a monomer, and subsequently Resin obtained by hydrogenation; ring-opening metathesis polymerization is carried out using tetracyclododecene or its derivative obtained by Diels-Alder reaction from dicyclopentadiene and olefins or (meth) acrylic acid or esters thereof as a monomer, Resin obtained by subsequent hydrogenation; ring-opening metathesis copolymerization of at least two monomers selected from norbornene, tetracyclododecene, derivatives thereof and other cyclic olefin monomers are similarly carried out, Resins obtained by hydrogenolysis; resins obtained by addition copolymerization of cyclic olefins and / or aromatic compounds having a vinyl group to cyclic olefins such as norbornene, tetracyclododecene, or derivatives thereof It can be mentioned.

  Typical examples of chain-like polyolefin resins are polyethylene resins and polypropylene resins. Among them, homopolymers of propylene or copolymers composed mainly of propylene and copolymerizable comonomers such as ethylene at a ratio of 1 to 20% by weight, preferably 3 to 10% by weight are preferred. It is preferably used.

  The polypropylene resin may contain an alicyclic saturated hydrocarbon resin. By containing the alicyclic saturated hydrocarbon resin, the retardation value can be easily controlled. The content of the alicyclic saturated hydrocarbon resin is advantageously 0.1 to 30% by weight with respect to the polypropylene-based resin, and a more preferable content is 3 to 20% by weight. When the content of the alicyclic saturated hydrocarbon resin is less than 0.1% by weight, the effect of controlling the retardation value can not be sufficiently obtained, while when the content exceeds 30% by weight, the protective film There is concern that bleeding out of the alicyclic saturated hydrocarbon resin may occur over time.

  Cellulose-based resin means that part or all of hydrogen atoms in hydroxyl groups of cellulose obtained from raw material cellulose such as cotton linta and wood pulp (hardwood pulp, softwood pulp) are substituted with acetyl group, propionyl group and / or butyryl group Or cellulose organic acid ester or cellulose mixed organic acid ester. For example, those composed of cellulose acetate, propionate, butyrate, mixed esters thereof and the like can be mentioned. Among them, triacetyl cellulose film, diacetyl cellulose film, cellulose acetate propionate film, and cellulose acetate butyrate film are preferable.

  As a method of using methyl methacrylate resin, polyethylene terephthalate resin, polyolefin resin, cellulose resin, etc. as a protective film for adhering to a polarizer, a method corresponding to each resin may be appropriately selected, It is not particularly limited. For example, a resin dissolved in a solvent is cast on a metal band or drum, the solvent is removed by drying to obtain a film, and the resin is heated and kneaded above its melting temperature and extruded from a die. A melt extrusion method is employed to obtain a film by cooling. In this melt extrusion method, extrusion of a single layer film may be used, or coextrusion of a multilayer film may be used. A retardation value can also be provided by performing stretching and / or shrinking and the like on a film formed of such a material.

  The protective films 20 and 21 can also contain additives as needed. Examples of the additive include lubricants, antiblocking agents, heat stabilizers, antioxidants, light resistance agents, impact modifiers and the like. The protective films 20 and 21 are preferably subjected to a saponification treatment, a corona treatment, a plasma treatment or the like prior to bonding with a polarizer.

  Commercially available films can be easily obtained as the protective films 20 and 21, and in the case of a methyl methacrylate resin film, Sumipex (manufactured by Sumitomo Chemical Co., Ltd.) and Acrilite (registered trademark) will be used under the respective trade names. Trademarks, Acriprene (registered trademark) (above, Mitsubishi Rayon Co., Ltd.), Deraglas (registered trademark) (Asahi Kasei Corporation), Paragrass (registered trademark), Comograss (registered trademark) (above, Kuraray Co., Ltd.), And Acrivia (registered trademark) (manufactured by Nippon Shokubai Co., Ltd.). In the case of polyolefin resin films, Zeonor (registered trademark) (Nippon Zeon Co., Ltd.), Arton (registered trademark) (JSR Corporation), etc. may be mentioned under the trade names. If it is a polyethylene terephthalate resin film, respectively, it is a brand name and Nova Clear (trademark) (made by Mitsubishi Chemical Co., Ltd.), Teijin A-PET sheet (made by Teijin Kasei Co., Ltd.), etc. are mentioned. For polypropylene-based resin films, FILMAX CPP film (manufactured by FILMAX), Santox (registered trademark) (manufactured by Sun Tox Co., Ltd.), Tosero (registered trademark) (manufactured by Tosoh Corp.), Toyobo Pyrene Film (Registered trademark) (made by Toyobo Co., Ltd.), Trefan (registered trademark) (made by Toray Film Processing Co., Ltd.), Nihon Polyace (made by Japan Polyace Co., Ltd.), and Taikei (registered trademark) FC (Futamura Chemical Co., Ltd.) And the like. In addition, as for the cellulose resin film, Fuji Tack (registered trademark) TD (manufactured by Fuji Film Co., Ltd.), KC2UA and Konica Minolta TAC film KC (manufactured by Konica Minolta Co., Ltd.), etc. may be mentioned under the trade names.

  When the protective films 20 and 21 are formed of the above-described resin film, the thickness of the resin film (does not include the thickness of the hard coat layer etc.) is usually about 1 to 50 μm, preferably 10 to 40 μm, and 10 to 30 μm. It may be

  A cured layer of an active energy ray curable resin composition may be used as the protective films 20, 21. Examples of the cured layer of the active energy ray curable resin composition include a layer that is cured by irradiating the active energy ray curable resin composition with active energy rays. Examples of the active energy ray-curable resin composition include those containing a polymerizable compound and a photopolymerization initiator, those containing a photoreactive resin, and those containing a binder resin and a photoreactive crosslinking agent. As the polymerizable compound, a photocurable monomer such as a photocurable epoxy monomer, a photocurable acrylic monomer, a photocurable urethane monomer, a photocurable liquid crystal compound, or an oligomer derived from the photopolymerizable monomer It can be mentioned. Examples of the photopolymerization initiator include those containing a substance that generates active species such as radicals, cations or anions upon irradiation of active energy rays such as ultraviolet rays. As the active energy ray-curable resin composition containing a polymerizable compound and a photopolymerization initiator, one containing a photocurable epoxy-based monomer and a photocationic polymerization initiator can be preferably used.

  The cured layer of the active energy ray curable resin composition is required after applying the active energy ray curable resin composition on the polarizer, the protective film, or the alignment film formed on the polarizer or the protective film. According to the above, it is obtained by performing a drying step and then curing the active energy ray curable resin composition by irradiating the active energy ray. The active energy ray to be irradiated can be appropriately selected from ultraviolet rays, electron beams, near ultraviolet rays, visible light, near infrared rays, infrared rays, X-rays and the like according to the type of the active energy ray curable resin. As the active energy ray, ultraviolet rays or electron beams are preferable, and ultraviolet rays are particularly preferable in that they are easy to handle and high energy can be easily obtained.

  The above composition may contain an additive. As an additive, an ion trap agent, an antioxidant, a chain transfer agent, a sensitizer, a tackifier, a thermoplastic resin, a filler, a flow control agent, a plasticizer, an antifoamer etc. are mentioned.

  The cured layer of the active energy ray curable resin composition is useful as a protective layer for protecting the surface of the polarizer. The cured layer of the active energy ray-curable resin composition can be made thinner than a conventional protective film, which is effective for thinning the polarizing plate. By using a photocurable liquid crystal compound, a desired phase difference can be imparted to the cured layer of the active energy ray curable resin composition as described later.

  0.01-20 micrometers is preferable, as for the thickness of the cured layer of an active energy ray curable resin composition, 0.01-10 micrometers is more preferable, More preferably, it is 0.01-5 micrometers.

  A phase difference may be given to the protective films 20 and 21. When the protective films 20 and 21 have a phase difference, the protective films 20 and 21 can be a λ / 4 plate, a λ / 2 plate, a positive C plate, or the like. The λ / 4 plate is a layer whose in-plane retardation value Re (550) at a wavelength of 550 [nm] satisfies the relationship of 100 nm ≦ Re (550) ≦ 200 nm. The λ / 4 plate may exhibit reverse wavelength dispersion satisfying Re (450) <Re (550) <Re (650). The λ / 2 plate is a satisfactory layer in which Re (550) satisfies 210 nm ≦ Re (550) ≦ 300 nm. The positive C plate satisfies the relationship of Nz> Nx = Ny, and the retardation value Rth (λ) in the thickness direction at the wavelength λ [nm] satisfies the relationship of −300 nm ≦ Rth (550) ≦ −20 nm Is preferred.

  When the protective films 20 and 21 have a phase difference, the protective films 20 and 21 may be formed of one type of retardation layer, or may be formed of a plurality of types of retardation layers. When the retardation layer comprises a plurality of retardation layers, a combination of a quarter wavelength plate and a half wavelength plate, and a combination of a quarter wavelength plate and a positive C plate are preferable.

  As a material which forms the protective films 20 and 21 which have a phase difference, the resin film illustrated above, the layer which the liquid crystal compound hardened | cured, etc. can be mentioned. In the case of forming the retardation film from a resin film, polycarbonate resins, cyclic olefin resins, styrene resins, and cellulose resins are preferable as the material. A retardation value can be provided by performing stretching and / or shrinking and the like on a film formed of such a material.

  Although the type of liquid crystal compound is not particularly limited, it can be classified into a rod-like type (rod-like liquid crystal compound) and a disk-like type (disk-like liquid crystal compound, discotic liquid crystal compound) from the shape. Furthermore, there are low molecular type and high molecular type, respectively. In addition, a polymer generally means a polymer having a degree of polymerization of 100 or more. A composition containing a liquid crystal compound having a polymerizable group is applied to a predetermined substrate to orient the liquid crystal compound to form a coating. The retardation layer can be produced by subjecting the obtained coating film to a curing treatment (irradiation with ultraviolet light (light irradiation treatment) or heat treatment). By selecting the thickness according to the material, a desired phase difference can be imparted. The produced retardation layer can be transferred, for example, on a polarizer or other film.

  A brightness enhancement film may be used as the protective film 20. The thickness of the brightness enhancement film is preferably 35 μm or less, more preferably 30 μm or less.

  As the brightness enhancement film, a polarization conversion element having a function of separating outgoing light from a light source (backlight) into transmission polarization and reflection polarization or scattering polarization is used. Such a brightness enhancement film can improve the output efficiency of linearly polarized light by utilizing the retroreflected light from the back light of the reflected polarized light or the scattered polarized light.

  As a brightness improving film, an anisotropic reflective polarizer is mentioned, for example. As an anisotropic reflective polarizer, there is an anisotropic multiplex thin film which transmits linearly polarized light in one vibration direction and reflects linearly polarized light in the other vibration direction. As an anisotropic multiplex thin film, the brand name "APF" made from 3M company is mentioned, for example. Further, as an anisotropic reflective polarizer, a composite of a cholesteric liquid crystal layer and a λ / 4 plate can be mentioned. As such a complex, there is a trade name "PCF" manufactured by Nitto Denko Corporation. Anisotropic reflective polarizers include reflective grid polarizers. Examples of the reflective grid polarizer include metal grating reflective polarizers in which metal is finely processed to emit reflected polarized light even in a visible light region. Above all, a brightness improving film made of an anisotropic multiple thin film is preferable.

(Hard coat layer 40)
The protective film 20 preferably has the hard coat layer 40 on the side opposite to the release film 60 side. By forming the hard coat layer 40, the moisture permeability of the protective film 20 can be reduced, and the puncture strength can be increased.

The protective film 20 on which the hard coat layer 40 is formed preferably has a surface resistance value of 1.0 × 10 ⁷ Ω / sq or more and 1.0 × 10 ¹⁰ Ω / sq or less, and 1.0 × 10 ^8. More preferably, Ω / □ or more and 1.0 × 10 ¹⁰ Ω / □ or less. With such a surface resistance value and the adhesive layer 30 having an antistatic function, a display device can be efficiently manufactured without causing multiple removal or product failure. The surface resistance value can be measured by the method described in the examples described later. In order to give the hard coat layer 40 the above-mentioned surface resistance characteristics, for example, the hard coat layer 40 may contain an antistatic agent. As the antistatic agent, conductive particles are preferably used because the puncture strength of the protective film 20 can be easily improved. By using the conductive particles, the piercing strength can be increased without increasing the film thickness of the hard coat layer.

  As the antistatic agent, various cationic compounds having a cationic group such as quaternary ammonium salt, pyridinium salt, and first to third amino groups; sulfonic acid base, sulfuric acid ester base, phosphoric acid ester base, phosphonic acid Anionic compounds having an anionic group such as a base; Amphoteric compounds such as amino acids and amino sulfates; Nonionic compounds such as amino alcohols, glycerins and polyethylene glycols; Organometallics such as alkoxides of tin and titanium Compounds; metal chelate compounds such as their acetylacetonate salts, and the like can be mentioned.

  In addition, an organic metal compound such as a coupling agent having a tertiary amino group, a quaternary ammonium group, or a metal chelate moiety and having a photopolymerizable monomer or oligomer, or a photopolymerizable functional group, etc. Photopolymerizable compounds can also be used as antistatic agents. These antistatic agents may be ionic liquids.

  The antistatic agent also includes a conductive polymer. The conductive polymer is not particularly limited, and, for example, aromatic conjugated poly (paraphenylene), heterocyclic conjugated polypyrrole, polythiophene, aliphatic conjugated polyacetylene, heteroatom containing conjugated polyaniline, mixed type Conjugated poly (phenylene vinylene), multi-conjugated type conjugated system having a plurality of conjugated chains in the molecule, and conductive polymer obtained by grafting or block-coiding the aforementioned conjugated polymer chain to a saturated polymer Sex complex etc. are mentioned.

The antistatic agent also includes conductive particles. Specific examples of the conductive particles include those made of metal oxides. Examples of such metal oxides include antimony-doped tin oxide (abbr .: ATO), phosphorus-doped tin oxide (abbr .: PTO), tin-doped indium oxide (abbr .: ITO), aluminum-doped zinc oxide (abbr .: AZO), gallium Mention may be made of doped zinc oxide (abbreviation: GZO), ZnO, CeO ₂ , Sb ₂ O ₅ , SnO ₂ , In ₂ O ₃ and Al ₂ O ₃ .

  The hard coat layer 40 can be formed by applying an active energy ray-curable resin composition on a resin film and then irradiating the active energy ray to cure the coating. When a photocurable resin or the like is used as the active energy ray curable resin, a photopolymerization initiator is usually contained in the coating liquid. Examples of the photopolymerization initiator include those containing a substance that generates active species such as radicals, cations or anions upon irradiation of active energy rays such as ultraviolet rays. It is preferable that it is 2-40 mass%, and, as for content of the antistatic agent with respect to the total solid of an active energy ray curable resin composition, it is preferable that it is 20-35 mass%. The composition may contain other additives such as solvents such as organic solvents, leveling agents, dispersants, antifouling agents and the like.

  The coating method of the composition may be a conventionally known method such as gravure coating, microgravure coating, roll coating, rod coating, knife coating, air knife coating, kiss coating, die coating and the like.

  The active energy ray to be irradiated can be appropriately selected from ultraviolet rays, electron beams, near ultraviolet rays, visible light, near infrared rays, infrared rays, X-rays and the like according to the type of the active energy ray curable resin. As the active energy ray, ultraviolet rays or electron beams are preferable, and ultraviolet rays are particularly preferable in that they are easy to handle and high energy can be easily obtained.

  The thickness of the hard coat layer 40 is, for example, preferably 0.01 to 20 μm, more preferably 1 to 10 μm, and still more preferably 3 to 7 μm. If the thickness of the hard coat layer is large, curling may easily occur due to curing shrinkage.

  The hard coat layer 40 may have, for example, functions such as antiglare property, light diffusion property, and antireflective property in addition to hard coat property. The hard coat layer 40 may be formed of a single layer or may be formed of a plurality of layers. When the hard coat layer 40 is composed of a plurality of layers, it can further include an antiglare layer, a light diffusion layer, an antireflective layer, a low refractive index layer, a high refractive index layer, and the like.

  The antiglare layer is an optical function layer provided with a predetermined uneven shape on the surface for preventing reflection of external light. The antiglare layer is, for example, a method of applying a coating liquid containing particles and a resin onto a transparent resin film, and then curing the coating layer as necessary (the surface unevenness due to the particles is (I) after coating a coating liquid (which may further contain organic particles and / or inorganic particles) containing a resin and particles on the resin film (i) It can be formed by a method of giving surface asperity to a coating layer, etc. by hardening a coating layer as needed, pressing the metal mold | die which has surface asperity shape as needed.

  The resin constituting the antiglare layer is not particularly limited as long as it has translucency. For example, in addition to the cured product of the active energy ray curable resin as described above, a cured product of a thermosetting resin; a thermoplastic resin; a metal alkoxide-based polymer, and the like can be used. Among them, a cured product of an active energy ray curable resin is preferable. When an ultraviolet curable resin is used as the active energy ray curable resin, the coating liquid contains a photopolymerization initiator (radical polymerization initiator) in the same manner as described above, and the coating is performed by irradiating the active energy ray. Cure the construction layer.

  As a thermosetting resin, the thermosetting urethane resin which consists of an acryl polyol and an isocyanate prepolymer, a phenol resin, a urea melamine resin, an epoxy resin, unsaturated polyester resin, a silicone resin etc. are mentioned. As a thermoplastic resin, the material of the above-mentioned protective film is illustrated.

  As a metal alkoxide type polymer, a silicon oxide type matrix etc. which use a silicon alkoxide type material as a raw material can be used. Specifically, the metal alkoxide polymer can be an inorganic or organic-inorganic composite matrix obtained by dehydration condensation of a hydrolyzate of alkoxysilane such as tetramethoxysilane or tetraethoxysilane.

  When using the hardened | cured material of a thermosetting resin, and a metal alkoxide type polymer as translucent resin, after coating a coating liquid, heating may be required.

  The particles may be used alone or in combination of two or more. In order to obtain desired antiglare properties and other optical properties, the type, particle diameter, refractive index, content, etc. of the particles are appropriately adjusted.

The light diffusion layer is an optical function layer for diffusing backlight light that has passed through the liquid crystal cell for the purpose of expanding the viewing angle of the liquid crystal display device and the like. The light diffusion layer is formed, for example, by applying a coating liquid containing particles (light diffusion agent) and light transmitting resin onto a transparent resin film and then curing the coating layer as necessary. be able to. As the particles and the light transmitting resin, those similar to those described for the antiglare layer can be used.
In order to obtain desired light diffusivity, the type of transparent resin film, the type of translucent resin, the type of particles, the particle diameter, the refractive index, the content, the thickness of the light diffusion layer, etc. are appropriately adjusted.

  The antireflective layer is an optical functional layer for reducing or preventing reflection of external light, and can be provided with, for example, a low refractive index layer. In addition, it may be a multilayer structure further including a high refractive index layer and / or a middle refractive index layer between the transparent resin film and the low refractive index layer.

The low refractive index layer needs a coating layer after applying a coating liquid containing a cured product of the above-mentioned active energy ray curable resin composition and a light transmitting resin such as a metal alkoxide polymer and inorganic particles. It can be formed by a method of curing according to. As the inorganic particles, for example, LiF (refractive index 1.4), MgF (refractive index 1.4), 3NaF · AlF (refractive index 1.4), AlF (refractive index 1.4), Na ₃ AlF ₆ ( Low refractive particles such as a refractive index of 1.33) and hollow silica particles may be mentioned.

  The high refractive index layer is coated after applying a coating liquid containing a light-transmissive resin such as a cured product of the above-mentioned active energy ray-curable resin or a metal alkoxide-based polymer and inorganic particles and / or organic particles. It can be formed by a method of curing the working layer as needed.

(Pressure-sensitive adhesive layer 30)
The pressure-sensitive adhesive layer 30 is a layer for bonding a polarizing plate to a display element such as a liquid crystal cell or an organic EL display element. The pressure-sensitive adhesive layer 30 has a creep force of 4.5 N or more and 15 N or less with the release film 60 described later. By setting the creep strength between the pressure-sensitive adhesive layer 30 and the release film 60 to 4.5 N or more and setting the puncture strength of the protective film 20 in the above-mentioned range, the curl of the laminate can be reduced. It is considered that the curl of the laminate can be reduced by reducing the deviation between the polarizing plate 10 and the release film 60 when the laminate is about to warp. From such a viewpoint, the creep force between the pressure-sensitive adhesive layer 30 and the release film 60 is preferably 5.0 N or more, and more preferably 6.0 N or more. On the other hand, by setting the creep force between the pressure-sensitive adhesive layer 30 and the release film 60 to 15 N or less, it is possible to suppress the floating of the release film 60 due to the progress of the adhesive force. From such a viewpoint, the creep force between the pressure-sensitive adhesive layer 30 and the release film 60 is preferably 14 N or less.

  The method of measuring the creep force between the release film and the pressure-sensitive adhesive layer will be described with reference to FIG. The produced laminate is cut into a size of 110 mm (length of double arrow 82) × 15 mm (length of double arrow 81). The middle point in the long side direction (dotted line 80) such that the length of the overlapping portion of the polarizing plate and the release film (the sum of the length of the double arrow 83 and the length of the double arrow 84) is 15 mm with respect to the long side direction. Cut off the peeling film and the polarizing plate on the end side from the position of 7.5 mm from the part shown in). Thus, a test piece having a shape as shown in FIG. 3 is produced. Attach the test piece to a tensile tester and measure the creep force. Specifically, one end of the test piece in the long side direction is gripped by the upper chuck and the other end is the lower chuck so that the long side direction of the test piece is perpendicular to the floor surface. Hold with. The lower chuck is moved downward so that the distance between the chucks expands at a speed of 1 mm / min, and the maximum force required for the movement is measured as the creep force until the movement distance becomes 5 mm.

  The creep force between the pressure-sensitive adhesive layer 30 and the release film 60 can be controlled, for example, by adjusting the amount of the crosslinking agent added to the pressure-sensitive adhesive layer. Further, since the creep force is also influenced by the peeling film 60 described later, a method of adjusting the release treatment of the peeling film 60 is also effective.

  Since the pressure-sensitive adhesive layer 30 has an antistatic function and the hard coat layer has a predetermined surface resistance value, it is possible to efficiently manufacture a liquid crystal display device without causing multiple removal or product failure. In order to provide the pressure-sensitive adhesive layer 30 with an antistatic function, for example, the pressure-sensitive adhesive layer 30 may contain an antistatic agent. That is, when the adhesive layer 30 contains an antistatic agent, it can be said that the adhesive layer 30 has an antistatic function. As the antistatic agent, those described above can be used. The antistatic agent of the pressure-sensitive adhesive layer may be the same as or different from the antistatic agent of the hard coat layer.

  The thickness of the pressure-sensitive adhesive layer 30 is preferably 5 to 40 μm, more preferably 10 to 30 μm, and still more preferably 15 to 25 μm.

  Examples of the pressure-sensitive adhesive forming the pressure-sensitive adhesive layer 30 include acrylic polymers, silicone-based polymers, polyesters, polyurethanes, polyamides, polyvinyl ethers, vinyl acetate / vinyl chloride copolymers, modified polyolefins, epoxy resins, fluorine-based resins, natural rubbers Those having a rubber-based polymer such as synthetic rubber as a base polymer can be appropriately selected and used. As the pressure-sensitive adhesive, those which are particularly excellent in optical transparency, exhibit appropriate adhesion properties such as wettability, cohesion and adhesiveness, and are excellent in weather resistance, heat resistance and the like are preferable.

  When an acrylic polymer is used as the base polymer of the adhesive, the weight average molecular weight Mw of the acrylic polymer is preferably 500,000 to 2,500,000, and more preferably 1,000,000 to 2,000,000. When the weight average molecular weight is 500,000 or more, the durability of the pressure-sensitive adhesive layer in a high temperature and high humidity environment can be improved. The operativity at the time of coating the coating liquid containing an adhesive as a weight average molecular weight is 2.5 million or less becomes favorable. The molecular weight distribution (Mw / Mn) represented by the ratio of the weight average molecular weight Mw and the number average molecular weight Mn of the acrylic polymer is preferably 2 to 10. The weight average molecular weight Mw and the number average molecular weight Mn are polystyrene equivalent values measured by gel permeation chromatography (GPC).

  The adhesive preferably further contains a crosslinking agent. The crosslinking agent is a divalent or higher metal ion which forms a carboxylic acid metal salt with a carboxyl group; a polyamine compound which forms an amide bond with a carboxyl group; poly Examples thereof include epoxy compounds and polyols which form an ester bond with a carboxyl group; and polyisocyanate compounds which form an amide bond with a carboxyl group. Among these, polyisocyanate compounds are preferable. It is preferable that the addition amount of the crosslinking agent with respect to 100 mass parts of base polymers is 0.15-1 mass part. Only one type of crosslinking agent may be added, or two or more types may be used in combination.

  The adhesive preferably contains a silane coupling agent. By containing a silane coupling agent, the adhesion between the pressure-sensitive adhesive layer and the adherend can be enhanced. The amount of the silane coupling agent added is preferably 0.01 to 10 parts by mass, more preferably 0.05 to 2 parts by mass, and 0.1 to 1 parts by mass with respect to 100 parts by mass of the base polymer. It is further preferred that Only one type of silane coupling agent may be added, or two or more types may be used in combination.

  Adhesives are fine particles for imparting light scattering properties, beads (resin beads, glass beads, etc.), glass fibers, resins other than base polymers, tackifiers, fillers (metal powders, other inorganic powders, etc.) And additives such as antioxidants, ultraviolet light absorbers, dyes, pigments, colorants, antifoaming agents, corrosion inhibitors, and photopolymerization initiators.

(Surface protection film 50)
The surface protection film 50 can include the base film 51 and the pressure-sensitive adhesive layer 52 laminated thereon. The surface protective film 50 is a film for protecting the surface of the polarizing plate 10, and usually, the pressure-sensitive adhesive layer 52 which the polarizing plate 10 has after being bonded to, for example, a display element or another optical member Be done.

  The surface protection film 50 generally has stiffness compared to the protection films 20 and 21 such as a brightness enhancement film, and is important for improving the releasability of the release film 60. The thickness of the surface protective film 50 is a total value of the thickness of the base film 51 and the thickness of the pressure-sensitive adhesive layer 52 laminated thereon, preferably 30 μm or more, and more preferably 50 μm or more. On the other hand, when the thickness of the surface protective film 50 is too large, when the peeling film 60 is peeled off, peeling easily occurs between the surface protective film 50 and the polarizing plate 10, so the thickness of the surface protective film 50 is preferably Is 100 μm or less, more preferably 70 μm or less.

  The base film 51 is preferably a thermoplastic resin film. The thermoplastic resin constituting the thermoplastic resin film is, for example, polyolefin resin such as polyethylene resin, polypropylene resin; cyclic polyolefin resin; polyester resin such as polyethylene terephthalate or polyethylene naphthalate; polycarbonate resin; A (meth) acrylic resin etc. can be mentioned. The substrate film may have a single layer structure or a multilayer structure.

  The thickness of the base film 51 can be 20 to 150 μm (eg, 30 to 80 μm, preferably 30 to 60 μm). About the composition of adhesive layer 52, the description about adhesive layer 30 which polarizing plate 10 mentioned above has is fundamentally quoted.

  In particular, the adhesive layer 52 has a storage elastic modulus at 80 ° C. of preferably 0.15 MPa or less, more preferably 0.14 MPa or less, and still more preferably 0.10 MPa or less. Usually, the storage elastic modulus at 80 ° C. of the pressure-sensitive adhesive layer 52 is 0.01 MPa or more. The storage elastic modulus of the pressure-sensitive adhesive layer can be measured using a commercially available visco-elasticity measuring device, for example, a visco-elasticity measuring device “DYNAMIC ANALYZER RDA II” manufactured by REOMETRIC.

  The surface protective film 50 can include an antistatic agent. The antistatic agent can be contained in the pressure-sensitive adhesive layer 52, for example. Instead of containing the antistatic agent in the pressure-sensitive adhesive layer 52, or together with this, on the surface of the base film 51 opposite to the surface on which the pressure-sensitive adhesive layer 52 is laminated, an antistatic layer containing the antistatic agent You may provide. Examples of the antistatic agent include antistatic agents that can be added to the hard coat layer.

(Peeling film)
The peeling film 60 is a film temporarily attached to protect the surface until the pressure-sensitive adhesive layer 30 is bonded to a display element (for example, a liquid crystal cell, an organic EL element) or another optical member. It is also possible to adjust the creep force with the pressure-sensitive adhesive layer 30 by subjecting the release film 60 to a release treatment with a release agent such as silicone or fluorine based on one side thereof. The peeling film 60 is comprised with the thermoplastic resin film by which the mold release process was carried out, and the adhesive layer 30 can be bonded together on the mold release process surface.

  The thermoplastic resin constituting the peeling film 60 may be, for example, a polyethylene-based resin such as polyethylene, a polypropylene-based resin such as polypropylene, or a polyester-based resin such as polyethylene terephthalate or polyethylene naphthalate. The thickness of the release film 60 is, for example, 10 to 50 μm.

  The peeling force between the pressure-sensitive adhesive layer 30 and the peeling film 60 is preferably 10 mN / 25 mm or more and 200 mN / 25 mm or less, and more preferably 40 mN / 25 mm or more and 100 mN / 25 mm or less. By setting it as the peeling force of such a range, the float of a peeling film can be suppressed and the peelability of a peeling film can be improved. The peeling force adopts a value when the peeling speed is 300 mm / min and the peeling angle is 180 °.

(Method of manufacturing laminate)
The members described above can be bonded to each other, for example, by laminating them via an adhesive layer or a pressure-sensitive adhesive layer, to produce a laminate. Each member may be cut into a predetermined shape and then stacked, or each member may be stacked by roll-to-roll and then cut into a predetermined shape. The shape of the laminate is not particularly limited. For example, the length of the long side may be 4.0 to 18.0 cm, and the length of the short side may be 3.0 to 9.0 cm. The laminated body may be subjected to a drilling process or may be processed into an R shape at the corner.

  The adhesive layer is, for example, a layer for bonding the polarizer 11 and the protective films 20 and 21. As the adhesive for forming the adhesive layer, mention may be made of an active energy ray-curable adhesive and a water-based adhesive. Can. Moreover, you may use the above-mentioned active energy ray curable resin composition.

  When using a water-based adhesive, it is preferable to carry out a drying step to remove water contained in the water-based adhesive after bonding the polarizer 11 and the protective films 20 and 21. After the drying step, for example, a curing step of curing at a temperature of about 20 to 45 ° C. may be provided.

  When using an active energy ray-curable adhesive, after bonding the polarizer 11 and the protective films 20 and 21, a drying process is performed if necessary, and then the active energy ray is cured by irradiating the active energy ray. Curing step of curing the adhesive. The light source of the active energy ray is not particularly limited, but ultraviolet light having a light emission distribution at a wavelength of 400 nm or less is preferable. Specifically, low pressure mercury lamp, medium pressure mercury lamp, high pressure mercury lamp, ultra high pressure mercury lamp, chemical lamp, black light lamp, micro A wave excitation mercury lamp, a metal halide lamp, etc. can be used.

  In bonding the polarizer 11 and the protective films 20 and 21, at least one of these bonding surfaces can be subjected to a saponification treatment, a corona treatment, a plasma treatment, or the like.

  The thickness of the pressure-sensitive adhesive layer that can be used to laminate the polarizer 11 and the protective films 20 and 21 (particularly, the brightness enhancement film) can be, for example, 3 to 15 μm. The material forming the pressure-sensitive adhesive layer can be selected from those exemplified for the pressure-sensitive adhesive layer 30 described above.

  The pressure-sensitive adhesive layer 30 is usually formed by applying a pressure-sensitive adhesive solution on a release sheet such as a release film 60 and drying it. The release sheet provided with the pressure-sensitive adhesive layer can be laminated on the polarizing plate 10 with the pressure-sensitive adhesive layer 30 interposed therebetween. When the release film 60 is used as a release sheet, a laminate can be obtained without attaching the release film 60. When a release sheet other than the release film 60 is used as the release sheet, the release sheet can be released once and the release film 60 can be laminated on the pressure-sensitive adhesive layer 30.

  The surface protective film 50 may be laminated on the protective film 20 in advance in the process of manufacturing the polarizing plate 10 or may be laminated on the protective film 20 after the polarizing plate 10 is manufactured. Although the curl of the laminate can be controlled by adjusting the tension when bonding the surface protective film 50, the control direction of the tension is limited to one direction. On the other hand, according to the present invention, since the pressure-sensitive adhesive layer 30 and the protective film 20 are used to control curling, the control factor is small in anisotropy, and curling can be controlled not only in one direction.

(Method of manufacturing display device)
FIG. 2 is a schematic cross-sectional view showing an example of the layer configuration of a display device using a laminate. In FIG. 2, the backlight and the polarizing plate on the back side are omitted. In the display device shown in FIG. 2A, a polarizing plate including a protective film 20, a polarizer 11 and an adhesive layer 30 in this order is laminated on one surface of a display element 70 via the adhesive layer 30. . In the display device shown in FIG. 2B, the protective film 20 having the hard coat layer 40 formed on one surface of the display element 70 via the adhesive layer 30, the polarizer 11, the protective film 21 and the adhesive layer A polarizing plate including 30 in this order is laminated.

  The polarizing film can be laminated on the display element 70 by peeling the peeling film 60 from the laminate and laminating the exposed adhesive layer 30 on the display element 70. When the polarizing plate has the surface protective film 50 on the protective film, the surface protective film 50 can be peeled off after laminating the polarizing plate on the display element 70.

  Examples of the display element 70 include a liquid crystal cell and an organic EL element. In an image display device, an image can be controlled by these image display elements. Liquid crystal cells, for example, in-plane switching (IPS) mode, vertical alignment (VA) mode, multi-domain vertical alignment (MVA) mode, continuous spin wheel alignment (CPA) mode, hybrid alignment nematic (HAN) mode, twisted nematic Any mode can be used such as (TN) mode, super twisted nematic (STN) mode, optically compensated bend (OCB) mode, and the like.

  The organic EL element is provided with a transparent electrode layer, a light emitting layer and an electrode layer in this order, and the light emitting layer can generate light when voltage is applied from the transparent electrode layer and the electrode layer. As an example of the material which comprises an organic light emitting layer, the material of a polypara phenylene vinylene type | system | group, a poly fluorene type | system | group, and a polyvinyl carbazole type can be mentioned. In addition, the light emitting layer may have a stack of a plurality of layers having different emission colors, or a mixed layer in which layers of certain dyes are doped with different dyes. Furthermore, the organic EL element may be provided with functional layers such as a hole injection layer, a hole transport layer, an electron injection layer, an electron transport layer, an equipotential surface forming layer, and a charge generation layer.

  Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not defined by these examples. In the examples,% and parts representing contents or amounts used are by mass unless otherwise specified. In addition, the evaluation method used in the Example is as follows.

(1) Thickness:
The measurement was performed using a digital micrometer MH-15M manufactured by Nikon Corporation.

(2) Creep force between the release film and the pressure-sensitive adhesive layer:
The method of measuring the creep force between the release film and the pressure-sensitive adhesive layer will be described with reference to FIG. The produced laminate was cut into a size of 110 mm (length of double arrow 82) × 15 mm (length of double arrow 81). The middle point in the long side direction (dotted line 80) such that the length of the overlapping portion of the polarizing plate and the release film (the sum of the length of the double arrow 83 and the length of the double arrow 84) is 15 mm with respect to the long side direction. The peeling film and the polarizing plate on the end side from the position of 7.5 mm were cut and removed respectively. The obtained test piece had a shape as shown in FIG. The test pieces were attached to a tensile tester (Autograph (registered trademark) AG-1S MO (floor setting) type, manufactured by Shimadzu Corporation), and creep force was measured. Specifically, one end of the test piece in the long side direction is gripped by the upper chuck and the other end is moved by the lower chuck so that both sides of the test piece are perpendicular to the floor surface. I held it. The lower chuck was moved downward so that the distance between the chucks was increased at a speed of 1 mm / min. The maximum force required for movement was measured as creep force until the movement distance reached 5 mm.

(3) piercing strength:
A puncture test of the protective film was performed. For the piercing test, a handy compression tester "KES-G5 needle penetration measurement specification" manufactured by Kato Tech Co., Ltd. equipped with a needle with a tip diameter of 1 mmφ and 0.5 R was used. The protective film was fixed to the tester by sandwiching the protective film with two jigs having a circular hole at the center. The needle is vertically lowered relative to the protective film through the hole of the jig to measure the strength when the protective film is broken. It carried out under the measurement conditions of 0.33 cm / sec of piercing speed in the environment of temperature 23 ± 3 ° C. The piercing strength measured in the piercing test was a piercing test on 12 test pieces, and the average value was taken. The thickness of the protective film was measured by the method described in the above (1), and the puncture strength per unit thickness of the protective film was determined.

(4) Moisture permeability:
The moisture permeability of the protective film was measured under the conditions of a temperature of 40 ° C. and a relative humidity of 90% by a cup method defined in JIS Z 0208.

(5) Peeling force:
Using an autograph (registered trademark) AGS-X, which is a bench-type precision universal tester manufactured by Shimadzu Corporation, the peeling force between the peeling film and the pressure-sensitive adhesive layer of the polarizing plate was measured. The peeling speed was 300 mm / min, and the peeling angle was 180 °.

(6) Surface resistance:
The surface resistance (Ω / □) of the protective film was measured using MCP-HT450 manufactured by Mitsubishi Chemical Analytech Co., Ltd. When the protective film had a hard coat layer, the surface resistance was measured in the state where the hard coat layer was formed.

(7) Evaluation of lift of release film:
The produced laminate was left in a normal temperature and normal humidity environment, and it was evaluated based on the following criteria whether floating (a phenomenon in which the peeling film peels off from the pressure-sensitive adhesive layer of the polarizing plate) occurs between the peeling film and the polarizing plate. .
○: No peeling occurred in the release film 9 months after production of the laminate ×: Lifting occurred in the release film 9 months after production of the laminate

(8) Evaluation of curl:
The produced laminate was cut into a size of 7 inches diagonal (155 mm × 87.2 mm), and conditioned for at least 3 hours in an environment of a temperature of 25 ° C. and a humidity of 60% RH. The laminate was placed on a flat table, a weight was placed at the center of the laminate, and the maximum value of the rising height at the end was measured. This evaluation was performed on the long side direction and the short side direction, and the averaged value was taken as the curling amount. The evaluation of curl was judged according to the following criteria.
○: absolute value less than 5.0 mm ×: absolute value 5.0 mm or more

(Production Example 1: Production of Polarizer)
A 30 μm thick polyvinyl alcohol film (average polymerization degree about 2,400, saponification degree 99.9 mol% or more) is uniaxially stretched about 5 times by dry stretching, and further kept at a tension of 60 ° C. After soaking in pure water for 1 minute, it was immersed in an aqueous solution of iodine / potassium iodide / water at a weight ratio of 0.05 / 5/100 at 28 ° C. for 60 seconds. Thereafter, it was immersed in an aqueous solution having a weight ratio of potassium iodide / boric acid / water of 8.5 / 8.5 / 100 at 72 ° C. for 300 seconds. Subsequently, the film was washed with pure water at 26 ° C. for 20 seconds, and then dried at 65 ° C. to obtain a 12 μm-thick polarizer in which iodine was adsorbed and oriented to a polyvinyl alcohol film.

Production Example 2: Preparation of Water-Based Adhesive
In 100 parts by weight of water, 3 parts by weight of a carboxyl group-modified polyvinyl alcohol (trade name "KL-318" obtained from Kuraray Co., Ltd.) is dissolved, and a polyamide epoxy based additive which is a water soluble epoxy resin is dissolved in the aqueous solution [Taoka An aqueous adhesive was prepared by adding 1.5 parts by weight of a trade name "Sumiles resin (registered trademark) 650 (30)" obtained from Chemical Industry Co., Ltd., an aqueous solution with a solid content concentration of 30% by weight].

(Example of polymerization of acrylic resins 1 and 2)
The acrylic monomer was charged in the amount shown in Table 1 in a reaction vessel equipped with a cooling pipe, a nitrogen introducing pipe, a thermometer and a stirrer. Ethyl acetate was added there to 150 parts per 100 parts in total weight of acrylic monomers to prepare a 40% solution of acrylic monomers. While replacing the air in the device with nitrogen gas to make it oxygen-free, raise the internal temperature to 55 ° C, and dissolve the entire solution of 0.14 parts of azobisisobutyro nitrile (polymerization initiator) in 10 parts of ethyl acetate Added. The temperature is maintained at this temperature for 1 hour after the addition of the polymerization initiator, and then ethyl acetate is continuously added to the reaction vessel at a rate of 17.3 parts / hr while maintaining the internal temperature at 54 to 56 ° C. When the concentration reached 35%, the addition of ethyl acetate was stopped, and the temperature was kept at this temperature for 12 hours after the start of the addition of ethyl acetate. Finally, ethyl acetate was added to adjust the concentration of the acrylic resin to 20% to prepare ethyl acetate solutions 1 and 2 of the acrylic resin. The weight average molecular weight Mw and Mw / Mn of polystyrene conversion which were calculated | required by GPC of the obtained acrylic resin are described in Table 1.

ＢＡ ：ブチルアクリレート
ＭＡ ：メチルアクリレート
ＨＥＡ ：２−ヒドロキシエチルアクリレート
ＡＡ ：アクリル酸
ＰＥＡ ：２−フェノキシエチルアクリレート
ＭＥＡ ：２−メトキシエチルアクリレート
ＢＭＡＡ ：２−ブトキシメチルアクリルアミド

BA: butyl acrylate MA: methyl acrylate HEA: 2-hydroxyethyl acrylate AA: acrylic acid PEA: 2-phenoxyethyl acrylate MEA: 2-methoxyethyl acrylate BMAA: 2-butoxymethyl acrylamide

(Preparation of adhesive layer)
The following pressure-sensitive adhesive layers were prepared.
Pressure-sensitive adhesive layer A: 1.2 parts of Coronate L (manufactured by Tosoh Corp.) as a crosslinking agent and 100 parts of solid content of the acrylic resin solution 2, and KBM-403 (manufactured by Shin-Etsu Chemical Co., Ltd.) as a silane coupling agent 0.5 parts of methyl ethyl ketone is added so that the solid content concentration is 14%, and the mixture is stirred and mixed at 300 rpm for 30 minutes using a stirrer [“three one motor” manufactured by Yamato Scientific Co., Ltd.] Agent composition A was prepared. Pressure-sensitive adhesive composition A after being dried using an applicator on the release-treated surface of a polyethylene terephthalate film (trade name "SP-PLR 382190" by Lintec Co., Ltd., called a release film) that has been subjected to release treatment It applied so that the thickness of a layer might be set to 20 micrometers, it was made to dry at 100 degreeC for 1 minute, and the adhesive layer A was produced.

Pressure-sensitive adhesive layer B: 0.6 parts of Coronate HXR (made by Tosoh Corp.) as a crosslinking agent and 100 parts of solids of the acrylic resin solution 1 and KBM-403 (made by Shin-Etsu Chemical Co., Ltd.) as a silane coupling agent 0.5 parts of methyl ethyl ketone is added so that the solid content concentration is 14%, and the mixture is stirred and mixed at 300 rpm for 30 minutes using a stirrer [“three one motor” manufactured by Yamato Scientific Co., Ltd.] Agent composition A was prepared. Pressure-sensitive adhesive composition A after being dried using an applicator on the release-treated surface of a polyethylene terephthalate film (trade name "SP-PLR 382190" by Lintec Co., Ltd., called a release film) that has been subjected to release treatment The solution was applied so that the thickness of the layer was 20 μm, and dried at 100 ° C. for 1 minute to prepare a pressure-sensitive adhesive layer B.

  Pressure-Sensitive Adhesive Layer C: A pressure-sensitive adhesive layer C was produced in the same manner as in the pressure-sensitive adhesive layer A except that the addition amount of Coronate L was changed to 0.4 parts.

  Pressure-Sensitive Adhesive Layer D: A pressure-sensitive adhesive layer D was produced in the same manner as in the pressure-sensitive adhesive layer A except that the addition amount of Coronate L was changed to 0.3 parts.

Pressure-Sensitive Adhesive Layer E: A pressure-sensitive adhesive layer E was produced in the same manner as in the pressure-sensitive adhesive layer B, except that the addition amount of Coronate L was changed to 0.2 parts.

  Pressure-Sensitive Adhesive Layer F: A pressure-sensitive adhesive layer F was produced in the same manner as in the pressure-sensitive adhesive layer B, except that the addition amount of Coronate L was changed to 0.1 part.

  Pressure-sensitive adhesive layer G: A pressure-sensitive adhesive layer G was produced in the same manner as in the pressure-sensitive adhesive layer B, except that the addition amount of Coronate L was changed to 0.05 parts.

(Preparation of protective film)
The following protective films were prepared.
Protective film A: A film in which a hard coat layer is formed on a cellulose resin film (KC2UA) (32 μm thickness, produced by Letterpress Printing Co., Ltd.). The hard coat layer contains an antistatic agent consisting of conductive particles.
Protective film B: A film in which a hard coat layer is formed on a cellulose resin film (KC2UA) (32 μm thickness, produced by Letterpress Printing Co., Ltd.). The hard coat layer contains no antistatic agent.
Protective film C: Cellulose resin film (Konica Minolta Co., Ltd., KC2UA, thickness 25 μm)
Protective film D: Cyclic olefin resin film (manufactured by Nippon Zeon Co., Ltd., ZF 14-013, thickness 13 μm)

Example 1
Protective film A was bonded to one side of the obtained polarizer via a water-based adhesive. The protective film D was bonded to the other surface of the polarizer via the same adhesive. After bonding, it was made to dry and the polarizing plate was produced. When bonding to the protective film A, it was made for the surface on the opposite side to the surface in which the hard-coat layer was formed to be a bonding surface with a polarizer. When bonding the protective film D, corona treatment was performed on the bonding surface of the protective film D.

  The adhesive B was coated on the protective film D to form an adhesive layer B. On the pressure-sensitive adhesive layer B, a release film (38 μm thick) made of a polyester resin and subjected to a release treatment was laminated. On the hard-coat layer with which the protective film A is equipped, the surface protection film provided with a polyester-type resin film (38 micrometers in thickness) and an adhesive layer (20 micrometers) was bonded via the said adhesive layer. Thus, a laminate having a layer configuration of surface protective film / protective film A / polarizer / protective film D / adhesive layer B / release film was produced.

The surface resistance value of the protective film A was 1.0 × 10 ¹⁰ Ω / □, and the peel force between the release film and the pressure-sensitive adhesive layer B was 70 mN / 25 mm. The results are summarized in Table 2.

[Examples 2 to 6, Comparative Examples 1 to 3]
A laminate was produced in the same manner as Example 1, except that the protective film A and the pressure-sensitive adhesive layer B were changed to those shown in Table 1. The peeling force between the pressure-sensitive adhesive layer and the peeling film is 50 mN / 25 mm in Examples 2 to 6 and Comparative Example 2, 150 mN / 25 mm in Comparative Example 1, and 30 mN / 25 mm in Comparative Example 3. The Moreover, in Examples 2-5 and Comparative Examples 1 and 3, the surface resistance value of the protective film was 1.0 × 10 ¹⁰ Ω / □. The surface resistance value of Example 6 and Comparative Example 2 was more than 1.0 × 10 ¹³ Ω / □ and could not be measured. The above results are summarized in Table 2.

  According to the present invention, it is useful because curling of a laminate including a polarizing plate and a release film can be reduced, and a laminate can be provided in which lifting of the release film is less likely to occur.

DESCRIPTION OF SYMBOLS 10 Polarizing plate 11 Polarizer 20, 21 Protective film 30 Pressure sensitive adhesive layer 40 Hard coat layer 50 Surface protective film 51 Base film 52 Pressure sensitive adhesive layer 60 Peeling film 70 Display element 80 Dotted line 81, 82, 83, 84 Double arrow 100, 101 laminate 200, 201 display device

Claims (6)

A laminate in which a polarizing plate and a release film are laminated in this order,
The polarizing plate includes a protective film, a polarizer, and an adhesive layer in this order,
The pressure-sensitive adhesive layer is disposed at a position adjacent to the release film,
The thickness of the polarizer is 15 μm or less.
The puncture strength of the protective film is 3.0 gf / μm or more,
The laminated body whose creep force of the said adhesive layer and the said peeling film is 4.5 N-15 N. The laminated body according to claim 1, wherein the moisture permeability of the protective film is 600 g / m ² · 24 hr or less. The laminate according to claim 1, wherein the protective film has a hard coat layer on the side opposite to the release film side. The laminate according to claim 3, wherein the surface resistance value of the hard coat layer is 1.0 × 10 ⁷ Ω / sq or more and 1.0 × 10 ¹⁰ Ω / sq or less. The laminate according to any one of claims 1 to 4, wherein the protective film contains at least one selected from a cellulose resin, a polycarbonate resin, a polyolefin resin, a polyethylene terephthalate resin, and a methyl methacrylate resin. . The laminated body in any one of Claims 1-5 which have a surface protective film on the opposite side to the said peeling film side on the basis of the said polarizing plate.

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